Clare Bremner had tried to get help for her mentally ill son about two weeks before he killed her.
Bremner was fatally stabbed by her son, Ross, while her husband Keith, was also attacked at their family home in Otorohanga last Tuesday.
He then went on and killed elderly Te Kuiti couple Mona Tuwhangai and Maurice O'Donnell at their remote Kawhia retreat some time later. Their bodies were found on Friday.
Bremner's neighbour, Dennis Kaumoana, told Fairfax, Clare Bremner had "big concerns" about Ross about two weeks before the deaths.
Kaumoana used to work at Tokanui mental health facilities, and recommended Clare phone the Henry Bennett Centre for an assessment.
She did and now it was too late.
"It's too late now. Everything is done now," Kaumoana said.
Kaumoana is also a relative of Mona and Maurice.
The Waikato DHB is reviewing its mental health care processes after Bremner's murderous rampage last week.
Bremner's father, Keith, remains fighting for his life in Waikato Hospital.
Police are still piecing together what happened as the two families begin to come to terms with the tragedies. They are yet to reveal if the knife has been recovered but suspect Mona and Morris may have lay dead for a "number" of days.
Bremner was believed to suffer from schizophrenia, which may have been drug-induced.
He had been under the care of the Waikato DHB.
DHB spokeswoman Lydia Aydon said an independent review will be carried out following the terrible events.
"Our thoughts are with the family and community at this difficult time," she said.
"Waikato DHB can confirm that Ross Bremner was a client of our Mental Health and Addiction Services and had been since 2003."
She said he had a number of brief inpatient stays in Henry Bennett Centre at Waikato Hospital from October 2003 to January 2007.
He had no further admissions until April 2013 when he spent six weeks in hospital. Since May 2013 he has been living in the community under the care of his GP and with the support of the "relevant DHB services".